Operation of a telephone switchboard or PBX is typically among the duties assigned to an office receptionist. In addition to connecting an incoming telephone call with the appropriate person within the office, the receptionist is often required to take messages when the desired party is unavailable. Receptionists are well aware that it is difficult to write a telephone message while cradling a conventional telephone handset between the head and shoulder. Therefore, so-called "hands free" telephone headsets have been designed which will operate with telephone base units. These headsets include a curved boom which positions a small microphone in close proximity to the front of the receptionist's mouth. An earphone is positioned at the other end of the boom so as to be adjacent to the receptionist's ear. A headband suspends the boom and earphone adjacent to the receptionist's face.
A very successful line of after market headsets have been designed for use with conventional telephone base units. Headsets of this type use the same four electrical connections between the headset and base unit as are present between a conventional telephone handset and a telephone base unit. Two of these electrical connections are receiving lines which receive electrical signals transmitted by the calling telephone to the earphone of the headset or handset of the called telephone. The remaining two electrical connections are transmitting lines which carry electrical signals from the microphone of the telephone headset or handset to the telephone base unit.
A continuing problem with the use of the now popular "hands free" telephone headsets is that only the receptionist is usually aware that he or she is currently "on line" with someone on the other end of the telephone. There are no visual cues to advise a guest or client in the reception area that the receptionist is listening to a speaker at the other end of the line. With conventional telephone handsets, it is abundantly clear that at least the telephone is "off the hook" whenever the receptionist cradles the telephone handset between his or her head and shoulder. With the telephone headset, however, the only visual cues which indicates that the receptionist is currently on the line is movement of the receptionist's lips. Clearly, this only occurs when the receptionist is talking and not listening. This motion is often difficult to see if the receptionist's head is slightly bowed, slightly turned, or if the receptionist is soft-spoken. Thus, a guest or client in the reception room may inadvertently interrupt a telephone conversation by addressing the receptionist when he or she is listening and is on the line. These situations are difficult for any receptionist to handle gracefully. In addition, even if the receptionist can politely inform the interrupting guest that he or she is currently on the line, such as by raising and index finger, the guest or client is often embarrassed and the receptionist's train of thought is broken thus possibly causing him or her to miss the message and requiring him or her to ask the caller to repeat the message.
Conventional, pre-electronic, multiple-line telephones are known which have a series of push-buttons illuminated by incandescent bulbs along the bottom edge of the telephone. Typically, a red hold button is provided at the right hand lower corner of the telephone base unit. Each of these transparent buttons, when illuminated, indicates that the handset has been removed from the base unit and that the base unit is on-line if the light is continuous. A flashing light indicates that another line is ringing. Nevertheless, these illuminated push-buttons are not located for effective viewing by guests in a reception area. Furthermore, these incandescent bulbs draw heavy currents and cannot advantageously use the low current signals which are present on the cable connecting the headset or hand set to the telephone base unit. Electronic telephones and PBX base units use solid state lighting devices to indicate that a particular line is in use, and that the base unit is on-line. Nevertheless, these lights are not appropriately positioned for viewing by a guest in a reception area, nor do these solid state devices advantageously use the signals which are present in the cable connecting a telephone headset to a base unit.
In view of the above, a need exists for a method and apparatus which will subtlety but clearly indicate to an observer that a telephone headset is currently in use with a telephone in the "on line" (or "off the hook") condition. Such method and device would preferably retrofit existing, conventional telephone base units and be adaptable to modern, electronic telephones.